We are investigating the ability of blocked isocyanate adducts based on tolylene-2,4-diisocyanate to form chemical bonds to dentin presumably through the amine groups that would be present in dentinal collagen. Most of the blocking agents employed are substituted phenols, some of which are used in dental practice. The high reactivity of these blocked NCO groups toward primary amine groups has been demonstrated using 1,3-diaminopropane as crosslinking reagent in reactions with both trimethylolpropane adducts and in copolymers of methyl methacylate containing blocked NCO groups. We have begun to look at the interaction of these latter copolymers with human dentin in vitro using attenuated total reflectance in the infrared and electron scanning for chemical analysis (ESCA). We will also study mechanical properties of polymeric materials based on blocked NCO functional copolymers.